Screw-cutter.



G. B. BURNS.

SCREW CUTTER.

APPLICATION FILED JUNE 13, 1910.

Patented May 28, 1912.

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SGREW CUTTER.

APPLIOATION FILED JUNE 18, 1910.

Patented May 28, 1912.

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C. B. BURNS.

SCREW CUTTER,

APPLICATION FILED JUNE 18, 1910.

Patented May 28, 1912.

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CHESTER BLAN'E BURNS, OF MOLINE, ILLINOIS.

SCREW-CUTTER.

Specification of Letters Patent.

Patented May 28,1912.

Application filed June 18, 1910. Serial No. 567,679.

To all whom it may concern:

Be it known that I, CHESTER B. BURNS, a citizen of the United States, residing at Moline, in the county of Rock Island and State of Illinois, have invented certain new and useful Improvements in Screw-Cutters; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in screw cutters, and the object of my invention is to provide a simple and compact device of this character in which chasers may be revolved either by hand or by power and readily adjusted.

lVith this object in view, my invention consists in the construction and combinations of parts as hereinafter described and claimed.

In the drawings-Figure 1 is an end view of my improved screw cutting device, the cover being removed and parts shown in section. Fig. 2 is a similar view of the chasers in a diflerent position. Fig. 3 is a longitudinal section of the same. Figs. 4, 5 and 6 are different views of one of the chaser blocks removed, and Fig. 7 is a side view of a modified form, the cover, chasers and chaser blocks being removed, a construction in which the chasers are driven by power.

.1 represents a sleeve by means of which the screw cutting device may be attached to a part of the lathe, and is provided with an opening 2 for the reception of a set screw. One end of the sleeve is enlarged, forming steps 3, 4 and 5; resting on the step 3, and against the step 4 is a casing 6 opened at both ends and cut away for the reception of a cover 7 which is attached thereto by means of screws 8, said cover having an overlapping edge leaving a space in which a ring 9 is mounted, which is used forthe purpose of adjusting the chaser blocks and chasers.

The ring 9, as shown in Fig. 1, may be revolved by means of a bent handle 10 provided with a worm wheel 11 engaging in a rack-19 on the ring 9, the shaft of the handle 10 being supported in a bent bracket 12. Resting on the step 4 and against the step 5 is an annular gear wheel 13 which meshes with a series of gear wheels 14, one for each chaser block. Each of these gear wheels is fixed on a shaft 20 which carries on its upper end a worm wheel 21. Each worm wheel 21 meshes with a worm 15 on the end of a shaft 16 on which is fixed a chaser 17 by means of the screw 18. The shaft 16 runs through a chaser block 22 and friction balls 23 are provided so that the chasers may revolve in the chaser blocks readily. The chaser blocks are of irregular shape, as shown in Figs. 4, 5 and 6, and are provided with trunnions 24 and 25, one of whlch is journaled in the cover 7 and the other in an inwardly extending and cut away port-ion 26 of the casing 6, the construction of all the chaser blocks being similar.

To adjust the chaser blocks in and out, for example, from the position shown in Fig. 1 to that shown in Fig. 2, the following means are provided. Each chaser block is provided with an outwardly flaring opening 27 and on a pin 28 passing across said opening into the sides of the block is journaled an arm 29 provided with a rounded head 30 which engages a rounded aperture in the ring 9. Set screws 31 are provided for adjusting the position of each chaser block at the beginning. There are shown in the drawings three of these chaser blocks carrying chasers for cutting threads, and in a similar chaser block 22 is mounted a guide 1 32 curved and provided with screw threads,

which work in the screw threads cut by the chasers. The cover is provided with a central hole 33, and the casing 6 is provided with a central hole 34, these being in line with the hole in the sleeve 1.

In operation the rod upon which the screw threads are to be cut is supposed to be rotated in the lathe, and the screw cutting device is supposed to be advanced over the rod, the chasers beingapproximately in the position shown in Fig. 1. As the screw cutting device is advanced, the revolving chasers cut the threads in the rod, the part 32 entering the threads and acting as a guide. 3

In operation, the device having been set to cut a screw-thread as indicated in Fig. 1, is placed in a lathe and by the mechanism therein advanced toward the rotating rod on which the screw-thread is to be cut, which enters the opening 33 and passes be tween the revolving chasers, the screwthread being cut thereby. lVhen the required length of thread has been cut, the chasers are disengaged from the rod by turning the handle 10, being brought into the position shown in Fig. 2.

In Fig. 7, a modified form is shown, in which the chasers are revolved by power instead of being revolved by coming in contact with the rotating rod on which the screw-thread is to be cut. Referring to this figure, the casing 35 has attached to it an extension 36, in which is mounted a shaft 37, driven by any suitable means (not shown) from the operating machinery. This shaft 37 has upon it a gear wheel 88, which meshes with a gear wheel 39, and this latter in turn meshes with an annular gear wheel 40. The gear wheel 40 meshes with four smaller gear wheels 4E1, the annular gear wheel 40 corresponding to the annular gear wheel 13 in Fig. 1 and the gear wheels or pinions 4:1 corresponding to the gear wheels l l in Fig. 1. In other respects, the construction is substantially the same as that shown in Fig. 1.

By the construction described, the revoluble chasers are so arranged that they are caused to revolve by the pitch of the screw which is being cut. This is of great importance, since no die can be started on a large shaft when a thread of coarse pitch is be ing cut thereon unless the chasers are free to revolve within the pitch of the screw be ing cut. Furthermore, by the construction described either a right or a left hand thread can be cut with the die cutting from instead of toward the spindle, as has hitherto been the case. To accomplish this, the die is opened by turning the handle 10 and passed over the work a distance equal to the length of the screw to be cut. Then, while the part on which the work is done is revolved, the die is closed by turning the handle 10, which causes the chasers to work their way into the rod. After the chasers have reached the bottom of the thread, the die is fed away from the spindle or the head of the screw, and in this manner the proper thread is obtained whether right or left handed.

hile I have thus described my invention, I do not limit myself to the exact details shown and described, as these could be varied considerably without departing from the spirit of my invention; for example, spiral or beveled gears could be used instead of the worm wheels and worms to drive the chasers.

I claim 1. In a screw cutter, the combination of a centrally perforated supporting casing, a centrally perforated sleeve engaging therewith, a plurality of revoluble chasers, a loose gear ring secured between said sleeve and casing, and connections between said gear ring and said chasers, whereby the latter are caused to move in unison, substantially as described.

2. In a screw cutter, the combination of a centrally perforated casing, a centrally perforated sleeve having steps thereon, a float ing gear ring held in position between the stepped sleeve and said casing, a plurality.

of revoluble chasers, and connections between said gear rmg and chasers, whereby said chasers are caused to revolve in unison,

thread guide, whereby they are all causedto revolve in unison, substantially as described.

4. In a screw cutter, the combination of a centrally perforated casing, a series of revoluble chasers, a chaser block supoprting said chasers, respectively, means for causing said chasers to revolve in unison, and means for simultaneously adjusting said chasers toward and away from each other, substantially as described.

5. In a screw cutter, the combination of a centrally perforated casing, a series of revoluble chasers mounted therein, a chaser block for each chaser and means for simultaneously adjusting said chaser blocks and chasers toward and away from each other, said means including a ring encircling said casing and provided with perforations, and a headed lever for each chaser block, having one end movably secured in said ring and the opposite end attached to the respective chaser block, and devices for moving said ring, substantially as described.

6. In a screw cutter, the combination of a centrally perforated casing, a series of revoluble chasers carried thereby, chaser blocks, one for each chaser, means for adjusting said chaser blocks and chasers simultaneously toward and away from each other, said means including a ring'mounted on said casing and provided with a series of perforations, a headed lever for each chaser block, one end of which is pivoted to said chaser block and. the headed end engages a perforation in said ring, and means for separately adjusting each chaser block in relation to its corresponding lever, substantially as described.

7. In a screw cutter, the combination of a centrally perforated casing, a series of revoluble chasers supported thereby, a chaser block for each chaser, means for causing said chasers to revolve in unison, means for adjusting said chasers simultaneously toward and away from each other, said means including a ring mounted on said casing, said ring being provided with perforations, a headed lever for each chaser block, one end being pivotally mounted in said chaser block and the other headed end engaging in a perforation in said ring, and means for operating said ring, and devices for adjusting each of said chaser blocks relatively to its corresponding lever, substantially as described.

8. In a screw cutter, the combination of a centrally perforated casing, a series of revoluble chasers and a revoluble thread guide mounted therein, a chaser block for each of said chasers and said thread guide, means for adjusting said chaser blocks simultaneously toward and away from each other, said means including a ring mounted on said casing, said ring being provided with perforations therein, a lever for each chaser block, having a headed end, one end of said lever being pivotally attached to the corresponding chaser block and the other end engaging said ring, and means for operating said ring, substantially as described.

9. In a screw cutter, the combination of a centrally perforated casing, a series of revoluble chasers and a revoluble thread guide, a chaser block for each of said chasers and said thread guide, means for adjusting said chaser blocks toward and away from each other simultaneously, and. separate adjusting devices for each chaser block, whereby the latter may be adjusted relatively to themain adjusting means, substantially as described.

10. In a screw cutter, the combination of a centrally perforated casing, a series of revoluble chasers and a revoluble thread guide supported thereby, a chaser block for each of said chasers and said thread guide, means for causing said chasers and said thread guide to revolve in unison, and means for simultaneously adjusting said chaser blocks toward and away from each other, including a perforated ring mounted on said casing, a lever for each chaser block, having one of its ends headed, said lever being pivotally attached at one end to the corresponding chaser block and having its headed end entering a perforation in said ring, and devices for partially revolving said ring, substantially as described.

11. In a screw cutter, the combination of a centrally perforated casing, a toothed perforated ring mounted on the outside thereof, a worm wheel provided with a handle, said worm wheel being the teeth on said ring, a series of revoluble chasers supported in said casing, a chaser block for each chaser, having a flaring opening in one of its sides, means for causing said chasers to revolve in unison, a lever for each chaser block having a headed end, one end entering the flaring opening in the chaser block and being pivoted to said block, and a 'pair of set screws passing through said chaser block and serving to adjust said lever, each of said levers having a headed end engaging in. one of the perforations of said ring, substantially as described.

12. In a screw cutter, the combination of a centrally perforated casing, a centrally perforated stepped sleeve resting against and partially within said casing, a floating gear ring loosely supported between said casing and the steps of said sleeve, a series of revoluble chasers, a chaser block for each chaser, means for simultaneously adjusting said chasers toward and away from each other, and means for causing said chasers to revolve in unison, said means including said floating gear ring, a series of short shafts, a pinion on each of said shafts engaging said gear ring, a second pinion on each of said shafts, and a chaser shaft for each chaser, pivotally mounted in the correspond ing chaser block and having a worm on one end engaging said second named pinion, substantially as described.

In testimony whereof, I affix my signature, in presence of two witnesses.

CHESTER BLANE BURNS. Witnesses:

GEORGE S. FITZGIBBON, ARTHUR G. LANE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C. 

